NIR Crosslinking Detection for Precured Resin Layers
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Solution Overview
Problem
Current methods for determining the degree of crosslinking of resin layers in wood-based panels are unreliable, leading to quality defects and increased costs due to incorrect residual moisture measurements, which do not accurately reflect the crosslinking state, especially in cases of overdrying or slow further crosslinking at room temperature.
Innovation Solution
A method using Near-Infrared (NIR) spectroscopy to determine the degree of crosslinking of thermosetting formaldehyde resin layers by comparing NIR spectra with reference samples, allowing for non-destructive, on-line analysis of the resin's state of curing, enabling quick and accurate assessment of the crosslinking state without material destruction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If residual moisture is determined by drying in an oven (VC determination), then a quality check is performed, but the measurement is inaccurate because it measures a sum parameter including water and formaldehyde split off, not the actual crosslinking state
Solution Approach 1:
The patent replaces the thermal drying method (mechanical/thermal system) with NIR spectroscopy (optical system) to determine crosslinking state. The NIR method directly measures the chemical state of the resin through spectral analysis, eliminating the need for oven drying and providing accurate crosslinking information without measuring only water loss.
Solution Approach 2:
The patent introduces NIR spectroscopy as an intermediary measurement technique that indirectly determines the crosslinking state by analyzing the spectral characteristics of the resin. This intermediary method provides accurate crosslinking information without directly disturbing the sample, unlike the destructive oven drying method.
2Reliability
If impregnates are overdried to ensure quality, then residual moisture is reduced, but the resin becomes too crosslinked and cannot flow or post-crosslink properly during further processing
Solution Approach 1:
The patent implements a feedback control system where NIR spectroscopy continuously monitors the crosslinking state of impregnates. Based on this real-time feedback, the drying process can be precisely controlled to achieve the optimal crosslinking state, preventing both under-curing and over-curing, and ensuring the resin remains processable while maintaining quality consistency.
Solution Approach 2:
The patent uses NIR spectroscopy to detect changes in the chemical parameters of the resin during drying. By monitoring spectral changes that indicate crosslinking progression, the process can be adjusted to maintain the resin in the desired B-state (partially crosslinked), balancing quality reliability with continued processability.
3Ease of manufacture
If traditional VC determination is used, then a quality check is performed, but it provides only a sum parameter and cannot detect slow further crosslinking at room temperature or overdrying issues
Solution Approach 1:
The patent replaces the thermal oven drying method (mechanical/thermal system) with NIR spectroscopy (optical system) to determine crosslinking state. The NIR method directly measures the chemical state of the resin through spectral analysis, eliminating the need for oven drying and providing accurate crosslinking information without measuring only water loss.
Solution Approach 2:
The patent introduces NIR spectroscopy as an intermediary measurement technique that indirectly determines the crosslinking state by analyzing the spectral characteristics of the resin. This intermediary method provides accurate crosslinking information without directly disturbing the sample, unlike the destructive oven drying method.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables rapid, non-destructive determination of the crosslinking state of resin layers, reducing production uncertainties and costs by providing immediate feedback on resin quality, allowing for precise control of processing conditions and minimizing defects in wood-based panel products.
Implementation Method 1
Recording of at least one NIR spectrum of the precured formaldehyde resin layer provided on the at least one carrier material using at least one NIR detector in a wavelength range between 500 nm and 2500 nm
Data Source
Figure 1~2
AI summary
The present invention relates to a method for determining the degree of crosslinking of at least one resin layer provided on a carrier material, the at least one resin layer being present on the carrier material in a precured state, comprising the steps of: recording at least one NIR spectrum of the at least one carrier material provided precured resin layer using at least one NIR detector in a wavelength range between 500 nm and 2500 nm, preferably between 700 nm and 2000 nm, particularly preferably between 900 nm and 1700 nm; Determining the degree of crosslinking of the at least one precured resin layer by comparing the NIR spectrum determined for the at least one precured resin layer with at least one NIR spectrum determined for at least one reference sample of the at least one resin layer with a known degree of crosslinking by means of a multivariate data analysis (MDA), wherein the at least an NIR spectrum determined for the at least one reference sample with a precured resin layer with a known degree of crosslinking using the same NIR detector in a wavelength range between 500 nm and 2500 nm, preferably between 700 nm and 2000 nm, particularly preferably between 900 nm and 1700 nm was determined.